Pipe couplings utilizing split collars received within grooves defined in the pipe circumference and utilizing elastomeric gaskets to seal the pipe circumferences are often employed with larger diameter pipes in view of the ease of assembly and fabrication as compared with threaded couplings, for instance. Additionally, such couplings have the advantage of accomodating slight misalignment between coupled pipe sections without adversely affecting the seal.
Pipe couplings of this type normally employ a split collar having a recess defined therein for accomodating a continuous annular elastomeric gasket generally of a C-shape transverse cross section. Such gaskets permit the sealing surfaces thereof to engage the pipe circumferences, and the interior of the gasket is usually in communication with the pipe ends permitting the medium being conveyed to enter the gasket cavity.
Such gasket cavities are commonly known as the "well", and the ability of the medium to enter the gasket well will create problems if the pipe is being used in locations wherein freezing of a liquid medium within the well can take place as such freezing can cause a deformation of the gasket and create leakage. Further, as the medium within the gasket is in a trapped condition bacterial action on the medium therein can contaminate the pipe joint, and in conduit systems processing foods and the like such a condition is intolerable. Also, gaskets having wells create turbulance and an undesirable flow resistance and medium agitation.
In order to overcome the aforementioned deficiencies of this type of gasket having a well, elastomeric gaskets have been developed utilizing transverse cross sections wherein portions of the gaskets continue to function as annular seals to engage the pipe periphery, but the gasket also includes an inwardly extending region which cooperates and engages with the ends of the pipe to seal and fill the spacing between the opposed pipe ends, and minimize or substantially prevent entry of the medium beyond the configuration of the pipe. Such gaskets are often of a generally E-shaped transverse cross sectional configuration, and may include nonhomogeneous gasket seals and elements which assemble to the primary gasket.
While gaskets having portions sealing the ends of the pipe, or interposed between the pipe ends, have been previously developed, those gasket constructions presently commercially available are of such configuration that voids exist in the gasket when in a compressed state which are capable of entrapping fluids and foreign matter, and while it is necessary that, in the relaxed state, this type of gasket include lip portions and an inwardly extending central region, the configuration and relationships of the various gasket portions of the prior art are not such as to completely eliminate voids while the gasket is under compression. U.S. Pat. Nos. 3,291,506 and 3,351,352 disclose gaskets of the described type generally of an E-configuration wherein escape of the transported medium around the conduit ends and into the gasket configuration is minimized. However, each of these patents disclose configurations which result in small voids within the gasket when under compression, and the presence of these voids provides the opportunity for entrapping water, liquids, foreign matter, bacteria, and other undesirable elements within the gasket which may result in gasket damage under freezing conditions, or result in contamination of the transported medium.